Network services, such as web services, are often implemented on various computing devices in a networked environment. A particular application implemented on a computing device may utilize application programming interfaces (API's) that are hosted on a remote computing device accessible via a network. Data store services can also be implemented on a remote data store and accessed by a particular application via the network. In such a network service environment, effectively and efficiently throttling access to a particular API, data store, or other network service can facilitate uptime and help ensure the various network services have sufficient capacity to provide services to application clients.